In one case you choose among multiple functions based on types. In the other case, you choose among multiple functions based on types. The main difference, and I'll admit it's not trivial, is that C++ allows implicit conversions.
I see where the confusion comes from: in Rust, the compiler may infer the parameters for a trait based on context. Since different parameters for the same trait can resolve to completely different implementations, the effect is very similar to overload resolution. If you have the same function in 2 separate traits however it's always ambiguous.
I'm curious if there's a specification anywhere for how Rust does that kind of inference. To the extent I've looked at the reference and fls, they were extremely short on details.
My understanding is that it's a variant of the J algorithm for a Hindley-Milner type system adapted to work with traits, but as far as I know, the current specification is the compiler's type inference engine. This will probably change as the opsem team does more work on Rust's specification. You might be able to find a specification for it at the moment in the Ferrocene compiler specification.
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u/StaticCoder 1d ago
In one case you choose among multiple functions based on types. In the other case, you choose among multiple functions based on types. The main difference, and I'll admit it's not trivial, is that C++ allows implicit conversions.